1. Cross Reference to Related Application
This application is related to copending U.S. patent application Ser. No. 07/725,216, filed Jun. 26, 1991, which is a continuation of U.S. patent application Ser. No. 07/357,512, filed May 25, 1989, by the present inventor. The related application is entitled "HIGH INTENSITY LIGHT DISPLAY DEVICE".
2. Field of the Invention
The present invention generally relates to visual displays, and more specifically to a visual display device which is especially suitable for automotive center-high-mounted stop-light (CHMSL) and brake light applications.
3. Description of the Related Art
Red colored CHMSLs for automotive vehicles are becoming increasingly popular due to the greatly increased safety margin they provide. In addition to the conventional right and left mounted, red-colored rear brake lights, newer vehicles and retrofit packages for older vehicles are available which include the CHMSL in the form of a third brake light which is mounted near the top of the vehicle rear window. Depression of the vehicle brake pedal causes the CHMSL to be illuminated in combination with the two low mounted brake lights to form a triangle pattern with greatly enhanced visibility and ability to immediately attract the attention of the operator of a trailing vehicle. Statistics have already proven that CHMSLs have prevented numerous traffic accidents in situations requiring emergency braking under high speed, congested traffic conditions.
A major problem which has persisted in providing a CHMSL on a conventional automotive vehicle is that existing devices generally include an opaque housing having a rear-facing translucent red panel with a white illuminating bulb inside the housing which is wired to the vehicle's brake circuit. The opaque housing itself constitutes a safety hazard in that it blocks a portion of the view through the rear window which the vehicle operator must see via the rear-view mirror in order to monitor the proximity of other vehicles. The opaque housing or at least a light blocking member (which may be the reflector) behind the illuminating bulb and red panel is necessary to prevent the vehicle operator from confusing the CHMSL with a light from another vehicle.
Conventional CHMSLs and brake lights including a white bulb, a large and bulky reflector and a red display panel which constitutes a red filter, are inefficient in that only the red component of light from the bulb is transmitted through the panel. All other colors or wavelengths of light are absorbed by the panel and thereby wasted. The result is that the intensity of the red light emitted by the device is considerably lower than the intensity of white light emitted by the bulb.
The above referenced related application discloses a CHMSL including a linear red light source, and a display panel having a first surface formed with optical quality, light reflecting grooves, which reflect and disperse light coupled from the light source into an edge of the display panel out a second surface of the panel which is opposite to the first surface. The display panel viewed from the first surface is transparent at all times. The display panel viewed from the second surface produces a red light pattern reflected from the grooves when the light source is turned on, and appears transparent when the light source is turned off.
Although highly effective in many applications, the CHMSL of the related application is not suitable for mounting on an automobile rear window which is tilted downwardly from the horizontal by a small angle (less than approximately 20.degree.), since the amount of light reflected out through the second surface of the panel in the horizontal direction is unacceptably small.